急！！！如何在jsp中把byte[]转换成image，然后在applet中显示出来？（分数可以再加）

我通过一个c++的exe程序输出一个jpeg图象的流，然后在jsp中取到后转成byte[],怎样在jsp中把byte[]转换成image，然后在applet中通过url调用jsp显示出来？
(c++是完成另一种格式的图象到jpeg的转换)

applet代码
import java.applet.*;
import java.awt.*;
import java.net.*;
import java.io.*;
import javax.swing.*;

public class export_jpeg extends Applet
{
  Image image;
  URL  iurl = null;
  String status="";
  public void init()
  {
   try{
    iurl=new URL  ("http://zhangxike:8080/clever/multiView/export_jpeg.jsp");

   image = Toolkit.getDefaultToolkit().getImage(iurl);

    }catch (Exception e)
     {
    System.out.println(e.getMessage());
     }

  }

  public void paint(Graphics g)
  {
     g.drawImage(image, 0, 0,this);
//     System.out.println("paint image wrong ....");

  }

}

jsp代码

<%@ page import="java.util.*" %>
<%@ page import="java.io.*" %>
<%@ page import="java.net.*" %>
<%@ page import="Management.*" %>
<%@ page import="javax.servlet.*" %>

<META HTTP-EQUIV="Content-Type" CONTENT="image/jpeg">

<%

    try {
    //execmange是完成调用exe程序
    ExecManage exec = new ExecManage();

    String[] parameter ={"dcmDisp.exe","D:/images/ST_2879_/SE_1____/IM001268"};

    InputStream istr=exec.runCommand(parameter);//取得jpeg数据流

    int ch = 0;
int i=0;
    ByteArrayOutputStream outp = new ByteArrayOutputStream();
    while( (ch=istr.read())!=-1 )
       {i++;
       outp.write(ch);
}
    System.out.println("i:"+i);
    byte[] b = outp.toByteArray();//转换成byte[]

    //怎样画出来？
    }
      catch (IOException e) {
System.err.println(e.getMessage());
}

%>

13 个解决方案

#1

you can use Servlet
http://softwaredev.earthweb.com/java/article/0,,12082_1488051_3,00.html
Acquiring a Binary Stream for the Response
Suppose you want to open a binary file in a browser from a servlet. It isn't text so you have to write the file to the servlet's output stream. Let's practice with a PDF document. First, you get the servlet's output stream with:

ServletOutputStream out = res.getOutputStream();
Next, you set the file type in the response object using one of the standard MIME (Multipurpose Internet Mail Extension) protocols. Several listings of content type names are available on the Internet including one at ftp://ftp.isi.edu/in-notes/iana/assignments/media-types. Then you use an HTTP response header named content-disposition. This header allows the servlet to specify information about the file's presentation. Using that header, you can indicate that the content should be opened separately (not actually in the browser) and that it should not be displayed automatically, but rather upon some further action by the user. You can also suggest the filename to be used if the content is to be saved to a file. That filename would be the name of the file that appears in the Save As dialog box. If you don't specify the filename, you are likely to get the name of your servlet in that box. To find out more about the content-disposition header, check out Resources or go to http://www.alternic.org/rfcs/rfc2100/rfc2183.txt.

Sending a binary stream to the client is not easy. Listing 4.10 will help you do it right.

Listing 4.10 Servlet That Sends a File to the Client
public class BinaryResponse extends HttpServlet {

  /**Set global variables*/
  public void init(ServletConfig config)
      throws ServletException
  {
   super.init(config);
  }

  /**Process HTTP Post request with doPost*/
  public void doPost(HttpServletRequest request,
           HttpServletResponse response)
    throws ServletException, IOException
  {

   String fileName = "index.html"; //set file name
   String contentType = getContentType(fileName);
   //contentType = getType(); //get the content type

   // get the file
   File file = new File(fileName);
   long length = file.length();
   if(length > Integer.MAX_VALUE)
   {
     //handle too large file error
     //perhaps log and return error message to client
   }
   byte[] bytes = new byte[(long)length];
   BufferedInputStream in =
    new BufferedInputStream(new FileInputStream(file));
   // then place it into a byte array
   if(length != in.read(bytes))
   {
     //handle too large file error
     //perhaps log and return error message to client
   }

   //get the servlet's output stream
   BufferedOutputStream out =
   new BufferedOutputStream(response.getOutputStream());
   //set the content type of the response
   response.setContentType( contentType );
   //send the file to the client
   out.write( bytes );
  }
}

  /**Clean up resources*/
  public void destroy()
  {
   //If you need to clean up resources.
   //Otherwise don't override.
  }
  String getContentType(String fileName)
  {
   String extension[] =
   {              // File Extensions
     "txt",            //0 - plain text
     "htm",            //1 - hypertext
     "jpg",            //2 - JPEG image
     "gif",            //3 - gif image
     "pdf",            //4 - adobe pdf
     "doc",            //5 - Microsoft Word
   },                // you can add more
   mimeType[] =
   {             // mime types
     "text/plain",         //0 - plain text
     "text/html",         //1 - hypertext
     "image/jpg",         //2 - image
     "image/gif",         //3 - image
     "application/pdf",      //4 - Adobe pdf
     "application/msword",     //5 - Microsoft Word
   },                // you can add more
   contentType = "text/html";    // default type

   // dot + file extension
   int dotPosition = fileName.lastIndexOf('.');
   // get file extension
   String fileExtension =
       fileName.substring(dotPosition + 1);
   // match mime type to extension
   for(int index = 0; index < MT.length; index++)
   {
     if(fileExtension.equalsIgnoreCase(
                  extension[index]))
     {
      contentType = mimeType[index];
      break;
     }
   }

   return contentType;
  }
}

#2

用servlet

#3

servlet生成的图象applet中怎么用，它们之间怎么连接？
servlet的数据源是通过exe程序生成的，取得后，要生成一个jpeg文件存放在硬盘上，而不是内存中？

#4

Image img=this.getToolkit().createImage(byte[],width,height);//用byte[]建立图象
显示的话，直接
g.drawImage(img,0,0,this);
------------
ok????!!!!

#5

// 保存为jpg图片的类

import com.sun.image.codec.jpeg.*;
import java.io.OutputStream;
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;

public class JPGWriter extends ImageWriter
{
     public void write(JComponent myComponent, OutputStream out) throws Exception
     {
       int imgWidth = (int)myComponent.getSize().getWidth(),
           imgHeight = (int)myComponent.getSize().getHeight();
       Dimension size = new Dimension(imgWidth,imgHeight);
       BufferedImage myImage =
         new BufferedImage(size.width, size.height,
         BufferedImage.TYPE_INT_RGB);
       Graphics2D g2 = myImage.createGraphics();
       myComponent.paint(g2);
       try {
         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
         encoder.encode(myImage);
         out.close();
       } catch (Exception e) {
            throw new Exception("GRAPHICS ERROR,CANNOT CREATE JPEG FORMAT");
       }
     }
}

#6

beyond_xiruo(希偌):
   byte[]是在jsp中取得的，在applet中通过
Image img=this.getToolkit().createImage(byte[],width,height)
得不到的。
我想通过jsp直接把byte[]输出成jpeg图象：
jsp内容类型：
  <META HTTP-EQUIV="Content-Type" CONTENT="image/jpeg">
   //
   byte[]  out.print出来
   //

这样applet通过URL就直接显示出来。

请问怎么办？

#7

Image img=this.getToolkit().createImage(byte[],width,height);
这个用法不仅仅是applet的，在其他地方也可以用

#8

在jsp中能用吗？

#9

byte[] b=new byte[4096];
Image img=java.awt.Toolkit.getDefaultToolkit().createImage(b,100,100);
这个在jsp里运行是正常的！

#10

beyond_xiruo(希偌) ：
我在jsp中生成的这个image对象在applet中怎么能用上呢？

#11

看看先

#12

你不是把生成的图象保存为.jpg了吗，用applet直接paint不就ok了吗？

#13

生成的图象不保存，只放在内存中，applet通过URL连接显示，可以实现吗？

#1

#2